For many years, it has been recognized that there is a need for a lightweight building material capable of soundproofing, insulation and fireproofing. This need has become severe due to the health hazards associated with asbestos which was for many years the principal source of fireproofing in buildings and which presently is being removed and replaced on an enormous scale in buildings located virtually throughout the world. In fact, some sources estimate that more than 170 million tons of asbestos have been used over the years with much of it still being in place.
In order to grasp the scope of the problem, asbestos was commonly mixed with paper and wool. The ratios were such that installations typically utilized 3% asbestos to 97% paper and wool. Clearly, there is an enormous need for a material that can replace asbestos.
However, an asbestos replacement must be a lightweight material for practical reasons. Since asbestos fireproofing is very lightweight, it is simply not feasible in many instances to utilize present cementicious fireproofing materials such as the product sold under the trademark "Monokote" by W. R. Grace & Co. or a similar material sold by U.S. Mineral Company, both of which are very heavy and do not contain sound proofing qualities. Without question, many buildings which require re-fireproofing were not designed for the weight of cementicious fireproofing materials.
By way of example, a one inch thick coating of "Monokote" applied to 100 square feet weighs on the order of 125 lbs. This is in contrast to asbestos fireproofing which only weighs on the order of one-fourth that amount. For construction based on asbestos fireproofing, the additional weight of cementicious fireproofing cannot be safely supported.
Moreover, while weight is a factor in asbestos replacement, cementicious fireproofing also has other serious drawbacks. This is true, for instance, in new construction where multiple coats of cementicious fireproofing must be applied in order to achieve desired thicknesses thereby escalating labor costs in its application and the very significant weight of cementicious fireproofing requires the use of heavier structural columns and beams due to the additional weight of this material. As a result, the cost of construction is escalated by reason of the necessity of oversized structural support.
While many different types of building insulation have been used, it is recognized as desirable to apply insulation directly to the wall, roof or other surface in buildings with open construction. It is for this reason that spray-on insulation and fireproofing such as those developed and utilized by W. R. Grace & Co., U.S. Mineral Company and others, which have an insulating component and an adhesive, have been used by applying monolithic coatings. Unfortunately, despite the fact that spray-on insulation and fireproofing has been used in the past, inexpensive products which can be applied easily and provide fireproofing have not been available.
Cellulose fiber has been used in spray-on insulation and fireproofing, and boric acid has been added to the cellulose fiber to increase the fire resistance thereof. The boric acid is, however, corrosive to metal and therefore disadvantageous when used in an insulation and fireproofing for metal buildings and, to eliminate the corrosive effect of the boric acid, other chemical agents must be used to buffer the acid. However, such chemical agents are expensive which significantly increases the cost while contributing nothing to the soundproofing and insulating qualities of the product.
As previously mentioned, the products of the type sold by W. R. Grace & Co. and U.S. Mineral Company have been relatively heavy. This adds substantial weight to the surface to be fireproofed. Since the composition is wet when first applied, and only thin layers can be applied due to the weight, usually not more than about one inch can be applied in a single application. This may typically result in a need for four coats to be applied in order to achieve a four inch coating of fireproofing. As will be appreciated, ample time must be allowed for drying between each coat before a subsequent coat can be applied.
Due to the multiple coats that are required, the cost of applying the material and the time required for applying the material are increased. It will also be appreciated that the application equipment must be set up for the separate applications and the operator's time is increased while applying the multiple coats that are required. Moreover, many materials such as cementicious fireproofing will often crack as a result of expansion and contraction of the surface to which it is applied.
While providing fireproofing, it would also be desirable to provide insulation and soundproofing as well, but cementicious fireproofing material does not possess these latter characteristics. In fact, the American Institute of Architecture has recently recognized that a single product that could both soundproof and fireproof would revolutionize the fireproofing industry.
Among the efforts to overcome the problems enumerated in detail hereinabove, Loomis U.S. Pat. No. 4,419,256 proposes a composition for insulation which may be used for reducing thermal transmission, for absorbing sound waves and for providing a fire spread barrier. Unfortunately, the composition includes the use of boric acid and is apparently capable of achieving only a one hour fire rating on a steel column based upon testing at Underwriters Laboratories. Despite the apparent lightweight nature of the composition, it has remained to provide a lightweight soundproofing, insulation and fireproofing material having all of the characteristics enumerated hereinabove.